Foundry mold

ABSTRACT

The invention consists of a mold for casting molten metal into desired shapes having a drag portion which is constructed of a permanent material such as graphite and a cope portion which is constructed of a destructible material such as resin bonded sand, the necessary sprue and risers being contained in the cope portion of the mold.

United States Patent Inventors William H. Owen Fultondale; Joe D. Marshall, Birmingham, Ala. Appl. No. 710,598 Filed Mar. 5, 1968 Patented Feb. 23, 1971 Assignee United States Pipe and Foundry Company Birmingham, Ala.

FOUNDRY MOLD 2 Claims, 1 Drawing Fig.

U.S. Cl.....i 164/342, 164/29,164/137,164/138,164/353,164/359, 164/361, 164/364 Int. Cl. 1322c 9/02, B22c 9/06 Field of Search 164/168,

339, 352, 359, 358, 362, 371, 21, (Wheel Digest); 164/29, 43, 137, 138, 342, 349, 353, 361, 364, 366

Primary ExaminerCharles W. Lanham Assistant Examiner-John E. Roethel Att0rney Robert F. Hess ABSTRACT: The invention consists of a mold for casting molten metal into desired shapes having a drag portion which is constructed of a permanent material such as graphite and a cope portion which is constructed of a destructible material such as resin bonded sand, the necessary sprue and risers being contained in the cope portion of the mold.

PATENTEU FEB23 Ian INVENTOR H- Owen Joe D. Manlmll ATTORNEY rouunnv MOLD Background of the lnvention 1. Field of the Invention In the foundry industry there are many casting that'are produced in large numbers which it would be desirable to produce in permanent molds. However, because of the configuration of the castings or the material being cast, the use of a permanent mold is either impossible or impractical. Accordingly the castings are made in varioustypes of sand molds which are usable for making only one" casting and which are made up of cope and drag portions.

2. Description of the Prior Art t In the manufacture of iron castings permanent metal or graphite molds have been used to a limited extent. However, only castings which can be made with a parting line that permits the casting to be removed from the two mold segments without damage tothe mold can be .made. For example, cast iron fittings can be made in metal molds because-their circular cross section permits them ,to be easilyextracted from the mold as it is opened'However, the casting must be removed very quickly upon solidification to prevent the solidified metal from tearing apart as the casting cools, and in-this tender condition they are easily damaged and precise control of the extraction time is difficult to attain.

SUMMARY or THE INVENTION .The present invention provides amold which is made up of a permanent graphite portion and a destructible resin-bonded sand portion. A portion of the casting surface is shaped by a cavity formed in a drag of permanent molding material such as a graphite block, and the remainder of the casting surface is formed in the cope portion which is made of resin sand. Since the resin sand cope is destructible-it does not matter if the casting contracts within it or that it cannot .be removed without destroying the mold. On the other hand, the portion of the casting formed in the drag portion must not hang up upon cooling and must be'easily removed without damage to the mold. a

DESCRIPTION OF TI-IE I JRAWING The DRAWING illustrates amold in section in which a follower ring for mechanical jointcast iron pipe has been cast. This casting is of polygonal shape'and has a-circular opening permitting it to be slipped over a pipe member, a series of bolt holes equally spaced around the central opening and a circular ringof metal adapted to be drawn against a packing gasket by means of bolts passing through the bolt holes.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, the drag portion 1 of the mold is a graphite cylinder, for example, a piece of arc furnace electrode, in which a cavity has been machined. The cavity is shaped to conform to part of the surface of the casting to be cast in the mold.-The molding surface is recessed into the graphite block sufficiently to permit thecope portion 3 of the mold to set in the cavity and cooperate with the drag 1 to form the casting cavity in which the follower ring 4 is formed. Since the cope 3 actually sets in the cavity 2 in the drag 1 it can easi ly be indexed in place and held properly aligned with the drag 1. It can be indexed by means of the sprue andriser cups which extend outward beyond the mainbody of the cope and The-cope 3 is preferably made of a resin-bonded sand, in other words it is a shell mold. In addition to forming the top portion of the casting, the cope 3 provides the sprue 5 and riser 6 through which metal is poured into the mold and the casting is fed during solidification. Although the sprue and riser are shown in the same vertical plane as the bolt holes 7, this would not normally be the practice, but instead, they would be situated in a vertical plane cutting between two adjacent bolt holes.

To make advantageous use of the present invention, it is preferred to mount several drag portions on on a turntable. At one position around the table the cope is set in place in the drag and a weight applied to keep the cope from floating. The mold then rotates to a pouring station where metal is poured into it after which it continues around the circle until it is solidified, and at a station remote from the pouring station the casting and cope portion of the mold are removed. By placing adequate molds on the turntable, the casting rate can be maintained at a rate which is limited only by the time required to pour one casting and index the next mold at the casting station.

If the drag portion becomes damaged or worn, it can either be repaired with graphite patching or a new molding surface can be machined into the graphite block at a deeper level. In this manner it is possible to obtain extensive use of one graphite block. Alternatively, the drag portion can be made of metallic material such as cast iron or mold steel. The shell mold portion of the mold is preferably kept to a minimum, and because of this it is possible to setup a unit which will cast large numbers of small castings without requiring an extensive sand system. Of course, the cope portion could also be made of baked sand or C0, hardened sand or any other destructible molding material that will provide an economical cope having sufficient strength to be handled and cast against with support from a flask.

From the foregoing it is apparent that the present invention permits the economical production of repetitively cast articles by combining pennanent molding with sand molding. By use of the present invention, the production of such articles can be undertaken with only a moderate investment in molding equipment. While there has been illustrated and described a presently preferred embodiment of the invention, it has been set forth in illustration of the invention and not as limitation of the invention. It will be apparent to those skilled in the art that charges may be made in mold materials and the procedures described without departing from the scope of the invention as set forth in the appended claims.

We claim:

1. A foundry mold comprising a drag portion of permanent molding material and having surfaces which form a cavity for shaping a portion of the surface of a casting and a cope portion consisting of a shell mold of destructible molding material having mold fonning surfaces which cooperate with said surfaces of said drag portion to shape the remaining surface of the casting, the cope portion being provided with sprue means for admitting molten metal to the casting forming cavity and riser means for controlling the amount of molten metal admitted to the casting forming cavity, a portion of said surfaces of said drag portion including indexing means for locating said cope portion relative to said drag portion and preventing relative reciprocal movement between said cope and drag portions, said indexing means of said drag portion consisting of a tapered wall portion so as to receive said cope portion in wedging engagement.

2. A foundry mold in accordance with claim 1 wherein, said sprue means and riser means include respective hollow cups, at least one of said cups constituting at least partially the radially outermost section of said cope portion and being in mu tually contacting and interfitting relationship with said index ing means of said drag portion so as to prevent relative rotational movement between said cope portion and said drag portion. 

2. A foundry mold in accordance with claim 1 wherein, said sprue means and riser means include respective hollow cups, at least one of said cups constituting at least partially the radially outermost section of said cope portion and being in mutually contacting and interfitting relationship with said indexing means of said drag portion so as to prevent relative rotational movement between said cope portion and said drag portion. 